How can I create a realistic floor water fountain
Your water is hitting the domain cube. Gravity is 32 feet per second square which is less then 10 meters per second. I don't even think fire hoses have a velocity of 100 meters per second. You are putting out way too much water, and it is hitting the top of the domain and flowing down the sides. You want it to shoot up and fall back on gravity without hitting anything.Try 10m/sec Z velocity on your inflow.